DOCSLIB.ORG

Change in Host Reproductive Status Induces Diapause in 1 Parasitoidsa

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Change in Host Reproductive Status Induces Diapause in 1 Parasitoidsa 1 Sex makes them sleepy: change in host reproductive status induces diapause in 2 parasitoidsa parasitoid population experiencing harsh winters 3 4 5 6 Tougeron K.1, 2, Brodeur J.2, van Baaren J.1, Renault D.1, 3 & Le Lann C.1 7 1 Univ Rennes, CNRS, ECOBIO (Ecosystèmes, biodiversité, évolution) - UMR 6553, 263 Avenue du 8 Général Leclerc, F-35000 Rennes, France. 9 2 Institut de Recherche en Biologie Végétale, Département de Sciences Biologiques, Université de 10 Montréal, 4101 rue Sherbrooke Est, Montréal, QC, Canada, H1X 2B2. 11 3 Institut Universitaire de France, 1 rue Descartes, 75231 Paris Cedex 05, France 12 13 14 Corresponding author: [email protected] 15 Current address: The University of Wisconsin – La Crosse, Department of Biology, La Crosse, 16 Wisconsin, United States of America, 1725 State street, 54601 17 18 19 20 1 21 Abstract 22 When organisms coevolve, any change in one species can induce phenotypic changes in 23 traits and ecology of the other species. The role such interactions play in ecosystems is central, 24 but their mechanistic bases remain underexplored. Upper trophic level species have to 25 synchronize their life-cycle to both abiotic conditions and to lower trophic level species’ 26 phenology and phenotypic variations. We tested the effect of host seasonal strategy on 27 parasitoid diapause induction by using a holocyclic clone of the pea aphid Acyrthosiphon pisum 28 producing two morphs with either asexual (and sexual morphs that are viviparous females) or 29 sexual ( (i.e. laying embryos) and oviparous females) reproduction (laying eggs), respectively, 30 the latter being only present at the end of the growing season. Aphidius ervi parasitoids from 31 populations of contrasted climatic origin (harsh vs. mild winter areas) were allowed to parasitize 32 each morph in a split-brood design and developing parasitoids were next reared under either 33 fall-like or summer-like temperature-photoperiod conditions. We next examined aspects of the 34 host physiological state by comparing the relative proportion of forty-seven metabolites and 35 lipid reserves in both morphs. produced under the same conditions. We found that oviparous 36 morphs are cues per se for diapause induction; parasitoids entered diapause at higher levels 37 when developing in oviparous hosts (19.4 ± 3.0 %) than in viviparous ones (3.6 ± 1.3 %), under 38 summer-like conditions (i.e.., when oviparous aphids appear in the fields). This pattern was only 39 observed in parasitoids from the harsh winter area since low diapause levels were observed in 40 the other population-dependent, suggesting local adaptations to overwintering 41 cues. Metabolomics analyses show parasitoids’ response to be mainly influenced by the host’s 42 physiology, with higher proportion of polyols and sugars, and more fat reserves being found in 43 oviparous morphs. Host quality thus varies across the seasons. and represents one of the 44 multiple environmental parameters affecting parasitoid diapause. Our results underline strong 45 coevolutionary processes between hosts and parasitoids in their area of origin, likely leading to 46 phenological synchronization, and we point out theirthe importance of such bottom-up effects 47 for trait-expression, and for the provision of ecosystem serviceservices such as biological 48 control in the context of climate change. 49 50 Key-words 51 Coevolution; Phenotypic plasticity; Phenology; Host-parasite synchronization; 52 Environmental cue; Metabolomics 53 54 55 56 2 57 Introduction 58 Interacting individuals from two biological entities can adjust their phenotypes in response to 59 cues from each other, even when these cues vary across time (Agrawal 2001). Beneficial or 60 antagonistic interactions, from mutualism to parasitism, predation and competition may lead to 61 adaptive phenotypic responses. When interactions persist over generations, coevolution can 62 occur and species adapt to the interacting species’ life history traits, phenology and ecology 63 (Agrawal 2001, Ellers et al. 2012). Interaction norms (Thompson 1988) arise from ecological 64 responses of interacting organisms in varying environments, as any phenotypic change 65 occurring in one ―partner‖ species can cascade to the other species’ phenotype (Fordyce 2006, 66 Hughes 2012). Cues produced by one interacting species may indirectly inform the other species 67 of environmental changes. For example, plant senescence in fall can inform herbivorous insects 68 of upcoming detrimental winter conditions and induces phenotypic changes (e.g. diapause 69 induction) or migration behaviour (Archetti et al. 2009). 70 Parasitoids are excellent models to study phenotypic expression in interacting species 71 because they are strongly influenced during immature stages by changes in nutritional and 72 physiological quality of their host (Godfray 1994). Diapause is an important ecological process 73 in insects allowing them to survive recurrent unfavorable environmental conditions (Tauber et 74 al. 1986). For parasitoids, diapause also contributes to maintain synchronization with their 75 host’s seasonal reproductive-cycle; it is induced before suitable hosts vanish from the 76 environment (Lalonde 2004). As in most insects, diapause in parasitoids is mainly induced by 77 abiotic cues perceived either by the generation that will enter diapause, or by the maternal 78 generation (Tauber et al. 1986). A few studies also reported that diapause in parasitoids can be 79 triggered by the onset of host diapause (Polgár and Hardie 2000, Gerling et al. 2009), or through 80 intraspecific competition for hosts (Tougeron et al. 2017a). However, whether the phenotype of 81 a non-diapausing host can influence parasitoid diapause remains poorly studied. 82 Aphids are hosts for Aphidiinae parasitoids and can have very complex cycles showing 83 seasonal alternation between morphs with asexual and sexual reproduction (Dixon 1985)(Dixon 84 1985). Asexual females reproduce parthenogenetically and lay live offspring (i.e. viviparity) 85 whereas sexualsexually reproducing females produce eggs (i.e. oviparity) after mating with 86 males. Sexual aphid morphs are present at higher proportions in harsh than in mild winter 87 climates (Dedryver et al. 2001)(Dedryver et al. 2001), and they represent the last hosts available 88 for aphid parasitoids before winter as they produce overwintering eggs in fall (Leather 89 1992)(Leather 1992). Consequently, sexual morphs have been suggested to promote diapause in 90 parasitoids, indicating a host physiological effect (Polgár et al. 1991, 1995, Christiansen- 91 Weniger and Hardie 1997)(Polgár et al. 1991, 1995, Christiansen-Weniger and Hardie 1997). 92 No mechanistic understanding of this phenomenon has been proposed and the effects of the host 93 morph have not been detangled from confounding factors such as host genotype and geographic 94 origin, host size, abiotic conditions, or the season at which hosts are sampled in the fields. Hosts 95 and parasitoids share common evolutionary historyhave coevolved over long periods of time, 96 they respond to similar seasonal cues and the physiological syndrome associated with 97 overwintering is highly conserved among insects (Tauber et al. 1986, Denlinger 2002)(Tauber et 98 al. 1986, Denlinger 2002). As a result, the related physiological state of the host may represent a 99 reliable signal of upcoming seasonal changes for parasitoids. 100 Hormones, fats, carbohydrates and other types of metabolites are involved in the control of 101 overwintering and diapause expression in insects (Chippendale 1977, Christiansen-Weniger and 3 102 Hardie 1999, Denlinger 2002, Sinclair and Marshall 2018). In aphid parasitoids, metabolomic 103 and proteomic profiles differ between diapausing and non-diapausing individuals, with higher 104 amounts of sugars, polyols and heat shock proteins being found in diapausing parasitoids 105 (Colinet et al. 2012). In aphids, morphs differ in morphology and physiology; oviparous females 106 accumulate reserves to produce energetically costly diapausing eggs (Le Trionnaire et al. 2008) 107 with cryoprotectant compounds such as mannitol and glycerol (Sömme 1969), whereas 108 viviparous females metabolize energetic resources rapidly to produce embryos. Aphids’ 109 triglyceride reserves change quantitatively and qualitatively across the seasons with alternating 110 morphs (Greenway et al. 1974). Immature parasitoids are known to consume sugars and lipids 111 from their hosts (Jervis et al. 2008) and are therefore influenced by host reserves for their 112 growth and development. 113 We questioned the extent to which oviparous and viviparous morphs of a single clone of the 114 pea aphid Acyrthosiphon pisum (Harris) (Hemiptera: Aphididae) influences winter diapause 115 expression in the parasitoid Aphidius ervi Haliday (Hymenoptera: Braconidae) under summer 116 and fall conditions. Under laboratory conditionsHormones, fats, carbohydrates and other types 117 of metabolites are involved in the regulation of overwintering and diapause expression in insects 118 (Chippendale 1977, Christiansen-Weniger and Hardie 1999, Denlinger 2002, Sinclair and 119 Marshall 2018). In aphid parasitoids, metabolomic and proteomic profiles differ between 120 diapausing and non-diapausing individuals, with higher amounts of sugars, polyols and heat 121 shock proteins being found in diapausing parasitoids (Colinet et al. 2012). In aphids, morphs 122 differ in morphology and physiology; oviparous females accumulate reserves
Load more

Recommended publications
  • Mating Behaviour of Aphidius Ervi (Hymenoptera: Braconidae): The
    Eur. J. Entomol. 99: 451-456, 2002 ISSN 1210-5759 Mating behaviourAphidius of ervi (Hymenoptera: Braconidae): The role of antennae Donatella BATTAGLIA1, Nunzio ISIDORO2, Roberto ROMANI3, F erdinando BIN3 and F rancesco PENNACCHIO1* 1Dipartimento di Biología, Difesa e Biotecnologie Agro-Forestali, Universita della Basilicata, Macchia Romana, 85100 Potenza, Italy. 2Dipartimento di Biotecnologie Agrarie ed Ambientali, Universita di Ancona, via Brecce Bianche, 60100 Ancona, Italy. 3Dipartimento di Arboricoltura e Protezione delle Piante, Universita di Perugia, Borgo XX Giugno 74, 06121 Perugia, Italy. Key words. Mating behaviour, ultrastructure, parasitoid, pheromone, functional anatomy, antennal glands, sensilla,Aphidius ervi, Aphidiinae Abstract. In the mating behaviour ofAphidius ervi Haliday the antennae play a pivotal role in partner recognition and acceptance. Mating failure was always observed when antennal contact was experimentally prevented. The maleA. of ervi has filiform antennae, consisting of scape, pedicel and 18-20 cylindrical antennomeres (flagellar segments), which bear numerous types of sensory struc­ tures and, interspersed among the multiporous plate sensilla, especially on the 1th and 2nd flagellar segments, scattered pores. A secretion oozes from these pores in virgin males exposed to conspecific females. Transmission electron microscopy revealed that these pores are the external openings of integumentary glands. Behavioural and morpho-functional observations indicated that a double step sex recognition mechanism is present in A. ervi, as in other parasitic Hymenoptera. Basically, female recognition by males appears to be mediated by a volatile sex pheromone, that triggers the behavioural sequence leading to mounting. Then, the female recognizes and accepts the male after antennal contact. This is mediated by the secretion that oozes from the male antennal glands, which acts as a contact pheromone.
    [Show full text]
  • Aphid-Parasitoid (Insecta) Diversity and Trophic Interactions in South Dakota
    Proceedings of the South Dakota Academy of Science, Vol. 97 (2018) 83 APHID-PARASITOID (INSECTA) DIVERSITY AND TROPHIC INTERACTIONS IN SOUTH DAKOTA Abigail P. Martens* and Paul J. Johnson Insect Biodiversity Lab South Dakota State University Brookings, SD 57007 *Corresponding author email: [email protected] ABSTRACT Parasitoid wasps of the subfamily Aphidiinae (Hymenoptera: Braconidae) specialize on aphids (Hemiptera: Aphididae) as hosts. The diversity of known and probable aphidiine wasps from South Dakota is itemized, with represen- tation by 13 genera and 42 species, 43% of which are probably adventitious. The wasps and aphids are central to various combinations of multitrophic relationships involving host plants and secondary parasitoids. Selected native and introduced aphid host taxa were quantitatively and qualitatively collected from diverse native and crop host plants in eastern South Dakota and western Iowa. Wasps were reared to confirm plant association, host aphid association, taxonomic diversity, and native or introduced status of the wasps. Acanthocaudus tissoti (Smith) and Aphidius (Aphidius) ohioensis (Smith) were found together on the native aphid Uroleucon (Uroleucon) nigrotuberculatum (Olive), a new host aphid species for both wasps on Solidago canadensis L. (Asterales: Asteraceae). The native waspLysiphlebus testaceipes (Cresson) was repeatedly reared in mas- sive numbers from mummies of invasive Aphis glycines Matsumura on soybean, Glycine max (L.) Merr. This wasp was also reared from the non-nativeAphis nerii Boyer de Fonscolombe and the native Aphis asclepiadis Fitch, both on Asclepias syriaca L. The introduced wasp Binodoxys communis (Gahan) was not recovered from any Aphis glycines population. Hyperparasitoids from the genus Dendrocerus Ratzeburg (Hymenoptera: Megaspilidae), and the pteromalid (Hymenoptera: Pteromalidae) genera Asaphes Walker, and Pachyneuron Walker were reared from mummies of Uroleucon (Uroleucon) nigrotuberculatum parasitized by either Acanthocaudus tissoti or Aphidius (Aphidius) ohioensis.
    [Show full text]
  • Diapause Expression in a Québec, Canada Population of the Parasitoid Aphidius Ervi (Hymenoptera: Braconidae)
    345 Diapause expression in a Québec, Canada population of the parasitoid Aphidius ervi (Hymenoptera: Braconidae) Kévin Tougeron1 , Joan van Baaren, Cécile Le Lann, and Jacques Brodeur Abstract—Aphidius ervi Haliday (Hymenoptera: Braconidae) is a major natural enemy of several agricultural pests in North America. Yet little is known about its overwintering strategy, especially concerning the plastic response to photoperiod and temperature that induce diapause. Information on parasitoid overwintering patterns is of great importance if we aim to predict their phenology and better inform pest outbreak control. Moreover, there is increasing evidence of plastic and genetic changes in overwintering strategies in insect from temperate areas following climate change. We set up a laboratory approach to better understand the factors acting on diapause induction in A. ervi.We studied the diapause incidence in a population from Québec, Canada, using the combination of two temperatures (14 °C and 20 °C) and three photoperiod treatments (10:14, 12:12, 14:10 [light:dark] hours). We found an effect of both factors on diapause incidence; A. ervi expressed close to 95% of diapause at the most fall-like conditions (14 °C, 10:14 [light:dark] hours) and almost no diapause (3.5%) at the most summer-like conditions tested (20 °C, 14:10 [light:dark] hours). This parasitoid species does have the potential to enter diapause in Québec before lethal frosts, despite a recent introduction from France (1960s), where mild winter occurs compared with Québec. Résumé—Aphidius ervi Haliday (Hymenoptera: Braconidae) est un des principaux ennemis naturels de plusieurs ravageurs agricoles en Amérique du Nord.
    [Show full text]
  • Survey of Internal Parasites of Potato-Infesting Aphids in Northeastern Maine, 1963 Through 1969
    SURVEY OF INTERNAL PARASITES OF POTATO-INFESTING APHIDS IN NORTHEASTERN MAINE, 1963 THROUGH 1969 W. A. Shands, Geddes W. Simpson, and Corinne C. Gordon A Cooperative Publication of the Life Sciences and Agriculture Experiment Station, University of Maine at Orono, and the Entomology Research Service, United States Department of Agriculture University of Maine at Orono TECHNICAL BULLETIN 60 AUGUST, 1972 CONTENTS Acknowledgment 2 Introduction 3 Procedure 4 Role of parasites in control of aphids on potato plants not treated with insecticides 5 Abundance of parasitized aphids on field-growing potatoes 5 Seasonal variation in abundance of the parasitized aphids 6 Average seasonal abundance of mummified potato- infesting aphids of three species 8 The parasites . 8 Parasites reared from the potato aphid 10 Parasites reared from the green peach aphid 11 Parasites reared from the buckthorn aphid 12 Parasites reared from the foxglove aphid 13 Summary and conclusions 14 References cited 1? ACKNOWLEDGMENT We are grateful to several entomologists of the Insect Identification and Parasite Introduction Branch, of the former Entomology Research Division, Agricultural Research Service, U. S. Department of Agricul­ ture, for assistance during the present study. These include P. M. Marsh, who identified the adult primary parasites in the family Braconidae, and adult hyperparasites in the family Ceraphronidae; B. D. Burks and W. A. Crawford, who identified the adult hyperparasites in the families Pteromalidae and Cynipidae; and R. I. Sailer, Chief of the Branch, who lent his support and encouragement. Research reported herein was supported in part by Hatch funds. Survey of Internal Parasites of Potato-Infesting Aphids in Northeastern Maine, 1963 through 1969 \V.
    [Show full text]
  • Effect of Diapause on Cold-Resistance in Different Life-Stages of an Aphid Parasitoid Wasp
    bioRxiv preprint doi: https://doi.org/10.1101/489427; this version posted December 8, 2018. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC 4.0 International license. Effect of diapause on cold-resistance in different life-stages of an aphid parasitoid wasp Authors and affiliations: Tougeron K.1, 2, Blanchet L.1, van Baaren J.1, Le Lann C.1 & Brodeur J.2 1 UMR 6553 Ecobio, Université de Rennes, Centre National de la Recherche Scientifique, 263 avenue du général Leclerc, 35042 Rennes, France. 2 Institut de Recherche en Biologie Végétale, Département de Sciences Biologiques, Université de Montréal, 4101 rue Sherbrooke Est, Montréal (QC), Canada H1X 2B2. Corresponding author: [email protected] This article is a preprint and has not been peer-reviewed Abstract To overwinter, insects from mild temperate areas can either enter diapause or remain active. Both strategies involve costs and benefits depending on the environment. In the first case, the emerging individuals will resist winter but have a reduced fitness because diapause entails physiological and ecological costs. In the second case, individuals need to be cold-resistant enough to withstand winter temperatures during their immature and adult stages, but could avoid diapause-associated costs. In mild temperate areas, the cost-benefit balance between the diapause and the non-diapause strategy would likely change in response to climate warming. A trade-off between these two strategies should lead to reduction of diapause expression in some populations.
    [Show full text]
  • Aspects, Including Pitfalls, of Temporal Sampling of Flying Insects, with Special Reference to Aphids
    insects Perspective Aspects, Including Pitfalls, of Temporal Sampling of Flying Insects, with Special Reference to Aphids Hugh D. Loxdale School of Biosciences, Cardiff University, The Sir Martin Evans Building, Museum Avenue, Cardiff CF10 3AX, Wales, UK; [email protected] Received: 10 September 2018; Accepted: 26 October 2018; Published: 1 November 2018 Abstract: Since the advent and widespread use of high-resolution molecular markers in the late 1970s, it is now well established that natural populations of insects are not necessarily homogeneous genetically and show variations at different spatial scales due to a variety of reasons, including hybridization/introgression events. In a similar vein, populations of insects are not necessarily homogenous in time, either over the course of seasons or even within a single season. This of course has profound consequences for surveys examining, for whatever reason/s, the temporal population patterns of insects, especially flying insects as mostly discussed here. In the present article, the topics covered include climate and climate change; changes in ecological niches due to changes in available hosts, i.e., essentially, adaptation events; hybridization influencing behaviour–host shifts; infection by pathogens and parasites/parasitoids; habituation to light, sound and pheromone lures; chromosomal/genetic changes affecting physiology and behaviour; and insecticide resistance. If such phenomena—i.e., aspects and pitfalls—are not considered during spatio-temporal study programmes, which is even more true in the light of the recent discovery of morphologically similar/identical cryptic species, then the conclusions drawn in terms of the efforts to combat pest insects or conserve rare and endangered species may be in error and hence end in failure.
    [Show full text]
  • The Effect of the Quality and Size of Host Aphid Species on the Biological Characteristics of Aphidius Colemani (Hymenoptera: Braconidae: Aphidiinae)
    Eur. J. Entomol. 105: 489–494, 2008 http://www.eje.cz/scripts/viewabstract.php?abstract=1356 ISSN 1210-5759 (print), 1802-8829 (online) The effect of the quality and size of host aphid species on the biological characteristics of Aphidius colemani (Hymenoptera: Braconidae: Aphidiinae) MARCUS VINICIUS SAMPAIO*, VANDA HELENA PAES BUENO and BRUNO FREITAS DE CONTI Universidade Federal de Lavras, Departamento de Entomologia, Caixa postal 3537, CEP 37200-000, Lavras-MG, Brazil; e-mail: [email protected] Key words. Aphidius colemani, Aphis gossypii, Aphidiidae, Aphidiinae, Braconidae, Brevicoryne brassicae, fitness, host quality, Myzus persicae, parasitoid, Rhopalosiphum maidis, Schizaphis graminum Abstract. A suitable host provides, at least, the minimum nutritional and physiological conditions for the development of the imma- ture stages of a parasitoid. Host quality may influence the developmental time, mortality rate, longevity and fecundity of parasitoids. This work evaluates the suitability and quality of Aphis gossypii Glover, Brevicoryne brassicae (Linné), Myzus persicae (Sulzer), Rhopalosiphum maidis (Fitch) and Schizaphis graminum (Rondani) as hosts for Aphidius colemani Viereck. Twenty second-instar nymphs of each aphid species were exposed to parasitism for one hour, and then kept in a climatic chamber at 22 ± 1°C, 70 ± 10% RH and a 12 h photophase. The aphid B. brassicae was unsuitable for the development of A. colemani. The different aphid host spe- cies varied in size: M. persicae > (R. maidis = S. graminum) > A. gossypii. Parasitoid fitness decreased accordingly when reared on (M. persicae = R. maidis) > S. graminum > A. gossypii. Large hosts seem to be better than small hosts based on parasitoid size. Egg load of A.
    [Show full text]
  • Compatibility of the Parasitoid Aphidius Matricariae with Botanigard for the Control of Greenhouse Aphids
    Compatibility of the parasitoid Aphidius matricariae with BotaniGard for the control of greenhouse aphids by Yasaman Norouzi B.Sc., Simon Fraser University, 2011 Thesis in Partial Fulfillment of the Requirements for the Degree of Master of Pest Management in the Department of Biological Sciences Faculty of Science ©Yasaman Norouzi 2013 SIMON FRASER UNIVERSITY Fall 2013 Approval Name: Yasaman Norouzi Degree: Master of Pest Management Title of Thesis: Compatibility of the parasitoid Aphidius matricariae with BotaniGard for the control of greenhouse aphids Examining Committee: Chair: John Reynolds Professor Jennifer Cory Senior Supervisor Professor Bernard Roitberg Supervisor Professor David Gillespie Supervisor Research Scientist Agriculture and Agri-Food Canada Deborah Henderson External Examiner Director Institute for Sustainable Horticulture Kwantlen Polytechnic University Date Defended/Approved: December 11, 2013 ii Partial Copyright Licence iii Abstract The simultaneous use of multiple biological control agents can be effective in suppressing pest populations, but the intraguild interactions that occur between biological control agents can disrupt biological control. I hypothesized that the combined use of the parasitoid, Aphidius matricariae, and the entomopathogenic fungi Beauveria bassiana (in the form of commercialized product, BotaniGard) for controlling the greenhouse aphid pest, Myzus persicae, would have a positive effect on pest control. Experiments were conducted in the laboratory over short periods and in greenhouses over multiple generations. Although BotaniGard had negative interactions with the parasitoids in short time scale experiments, over an extended time the combined use of BotaniGard and parasitoids had synergistic effects on aphid suppression. The number of parasitoids present at the end of the experiments in longer-scale experiments was higher in treatments with BotaniGard application than in treatments with parasitoids alone.
    [Show full text]
  • Offspring Sex Ratios in Parasitoid Wasps
    This is an electronic version of the content of the article published as King, B.H. 1987. Offspring sex ratios in parasitoid wasps. Quarterly Review of Biology 62:367-396. The original publication is available at http://www.jstor.org/stable/2829455 ABSTRACT Laboratory and field studies on about 100 species in sixteen families indicate that several factors can influence offspring sex ratios in parasitoid wasps. For many species, offspring sex ratio increases with one or more of the following: 1) maternal age at ovipositing or the amount of time since insemination, 2) the age of the male parent or the number of times he has copulated, 3) extreme temperature, 4) decreasing host size, age, or quality, 5) female wasp density, and 6) the number of progeny per host. Other factors which have been shown to affect offspring sex ratios in some species include: 1) number of hours since insemination, 2) genetic factors, 3) maternal size, 4) maternal diet, 5) polyembryony, 6) photoperiod and relative humidity, 7) host sex, and 8) host density. These factors may affect offspring sex ratios through females manipulating fertilization of their eggs or through other mechanisms such as differential mortality or changes in sperm availability. Theoretical development has focused primarily on females manipulating their offspring sex ratios in response to host size and/or to female density. Host size models predict a negative relationship between offspring sex ratio and host size. These models assume that host size has a greater effect on the reproductive success of females than of males. LMC models predict a positive relationship between offspring sex ratio and female density.
    [Show full text]
  • University Microfilms International 300 N
    INFORMATION TO USERS This reproduction was made from a copy of a document sent to us for microfilming. While the most advanced technology has been used to photograph and reproduce this document, the quality of the reproduction is heavily dependent upon the quality of the material submitted. The following explanation of techniques is provided to help clarify markings or notations which may appear on this reproduction. 1. The sign or "target" lor pages apparently lacking from the document photographed is "Missing Pagets)". If it was possible to obtain the missing pagets) or section, they are spliced into the film along with adjacent pages. This may have necessitated cutting through an image and duplicating adjacent pages to assure complete continuity. 2. When an image on the film is obliterated with a round black mark, it is an indication of either blurred copy because of movement during exposure, duplicate copy, or copyrighted materials that should not have been filmed. For blurred pages, a good image o f the page can be found in the adjacent frame. If copyrighted materials were deleted, a target note will appear listing the pages in the adjacent frame. 3. When a map, drawing or chart, etc., is part of the material being photographed, a definite method of "sectioning” the material has been followed. It is customary to begin filming at the upper left hand com er o f a large sheet and to continue from left to right in equal sections with small overlaps. If necessary, sectioning is continued again beginning below the first row and continuing on until complete.
    [Show full text]
  • Forest Health Technology Enterprise Team
    Forest Health Technology Enterprise Team TECHNOLOGY TRANSFER Biological Control September 12-16, 2005 Mark S. Hoddle, Compiler University of California, Riverside U.S.A. Forest Health Technology Enterprise Team—Morgantown, West Virginia United States Forest FHTET-2005-08 Department of Service September 2005 Agriculture Volume II Papers were submitted in an electronic format, and were edited to achieve a uniform format and typeface. Each contributor is responsible for the accuracy and content of his or her own paper. Statements of the contributors from outside of the U.S. Department of Agriculture may not necessarily reflect the policy of the Department. The use of trade, firm, or corporation names in this publication is for the information and convenience of the reader. Such use does not constitute an official endorsement or approval by the U.S. Department of Agriculture of any product or service to the exclusion of others that may be suitable. Any references to pesticides appearing in these papers does not constitute endorsement or recommendation of them by the conference sponsors, nor does it imply that uses discussed have been registered. Use of most pesticides is regulated by state and federal laws. Applicable regulations must be obtained from the appropriate regulatory agency prior to their use. CAUTION: Pesticides can be injurious to humans, domestic animals, desirable plants, and fish and other wildlife if they are not handled and applied properly. Use all pesticides selectively and carefully. Follow recommended practices given on the label for use and disposal of pesticides and pesticide containers. The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, sex, religion, age, disability, political beliefs, sexual orientation, or marital or family status.
    [Show full text]
  • The Potential for Dickeya Dianthicola to Be Vectored by Two Common Insect Pests of Potatoes
    The University of Maine DigitalCommons@UMaine Electronic Theses and Dissertations Fogler Library Fall 12-20-2019 The Potential for Dickeya dianthicola to be Vectored by Two Common Insect Pests of Potatoes Jonas K. Insinga University of Maine, [email protected] Follow this and additional works at: https://digitalcommons.library.umaine.edu/etd Part of the Agricultural Science Commons, Animals Commons, Bacteria Commons, Bacteriology Commons, Behavior and Ethology Commons, Biochemistry Commons, Biosecurity Commons, Entomology Commons, Environmental Microbiology and Microbial Ecology Commons, Epidemiology Commons, Integrative Biology Commons, Laboratory and Basic Science Research Commons, Other Animal Sciences Commons, Pathogenic Microbiology Commons, Plant Pathology Commons, Plants Commons, and the Zoology Commons Recommended Citation Insinga, Jonas K., "The Potential for Dickeya dianthicola to be Vectored by Two Common Insect Pests of Potatoes" (2019). Electronic Theses and Dissertations. 3117. https://digitalcommons.library.umaine.edu/etd/3117 This Open-Access Thesis is brought to you for free and open access by DigitalCommons@UMaine. It has been accepted for inclusion in Electronic Theses and Dissertations by an authorized administrator of DigitalCommons@UMaine. For more information, please contact [email protected]. THE POTENTIAL FOR DICKEYA DIANTHICOLA TO BE VECTORED BY TWO COMMON INSECT PESTS OF POTATOES By Jonas Klair Insinga B.A., University of New Hampshire at Durham, 2012 A THESIS Submitted in Partial Fulfillment of the Requirements for the Degree of Master of Science (in Entomology) The Graduate School The University of Maine December 2019 Advisory Committee: Andrei Alyokhin, Professor of Applied Entomology, Advisor Jianjun Hao, Associate Professor of Plant Pathology Allison Gardner, Assistant Professor of Arthropod Vector Biology © 2019 Jonas Klair Insinga All Rights Reserved ii THE POTENTIAL FOR DICKEYA DIANTHICOLA TO BE VECTORED BY TWO COMMON INSECT PESTS OF POTATOES By Jonas Klair Insinga Thesis Advisor: Dr.
    [Show full text]